1. Field
The described technology relates generally to a method for inspecting a polysilicon layer. More particularly, the described technology relates generally to a method for inspecting the crystallinity and/or crystal structure of a polysilicon layer.
2. Discussion of the Background
Most flat panel display devices, such as an organic light emitting diode (OLED) display, a liquid crystal display (LCD), and the like, include a thin film transistor. Particularly, a low temperature polycrystalline silicon thin film transistor (LTPS TFT) having good carrier mobility can be applicable to a high speed operational circuit and can be used for a CMOS circuit, so the LPTS TFT has been commonly used.
A LTPS TFT includes a polysilicon film that is formed by crystallizing an amorphous silicon film. Methods for crystallizing the amorphous silicon film include solid phase crystallization, excimer laser beam crystallization, and metal catalyst crystallization.
Laser beam crystallization has been widely used because it is a relatively low temperature process that reduces the thermal deformation of a substrate and can be used to produce a polycrystalline silicon layer having excellent carrier mobility.
In order to determine whether a polysilicon layer is appropriately crystallized, light is radiated onto the polysilicon layer, and light discharged by the polysilicon layer is analyzed, in order to determine whether the polysilicon layer has a defect.
In order to properly determine the existence of the defect, the intensity of the excitation light radiated onto the polysilicon layer are conventionally be relatively high, and in this case, the thin-film polysilicon layer may be damaged.
The above information disclosed in this Background section is only for enhancement of the understanding of the background of the described technology, and therefore, it may contain information that does not constitute prior art.